Method for coating implantable devices

ABSTRACT

Coating an implantable device, such as micro electromechanical devices, is highly desirable to protect the implantable device from corrosion. A coating method includes depositing, preferably by plasma glow discharge, a reactant monomer on at least one surface of an implantable device, preferably at ambient temperature. The method will likely decrease the manufacturing time required for assembling such devices because completely assembled devices can be coated.

FIELD OF THE INVENTION

[0001] The present invention relates to a method for coating microelectromechanical devices to provide coatings on such devices that arerelatively corrosion-resistant and suitable for in vivo implantation,such as within a human body.

BACKGROUND

[0002] In many medical situations, it is desirable and often necessaryto implant relatively small (micro) electromechanical devices for anextended period of time. For example, it may be desirable to continuallyadminister fluid medication (either as a gas or a liquid) to a patientover an extended period of time. Examples of such treatments includedthe low dose continual administration of morphine for pain control, theadministration of FUDR for cancer chemotherapy, the administration ofbaclofen for the treatment of intractable spasticity, and the like.

[0003] In such instances, a particularly desirable goal is to maintain arelatively constant level of medication in the patient's bloodstream. Inorder to accomplish this goal, relatively small fluid handling devicesare implanted within a patient's body. However, both the medication andbodily fluids that may contact the micro fluid handling devices aretypically corrosive. Thus, it is desirable to provide acorrosion-resistant layer to at least one surface of the micro fluidhandling device to prevent or limit corrosion. For example, a nominallayer of a corrosion-resistant substance may be deposited on a substrateby sputtering by using an e-beam evaporator, where suitablecorrosion-resistant substances may be silicon, gold, platinum, chrome,titanium, zirconium, and oxides of silicon or these metals. See, U.S.Pat. Nos. 5,660,728; 5,702,618; and 5,705,070 all to Saaski et al. It isdescribed that the oxides may be formed by thermally oxidizing thecorrosion-resistant substance in air after it has been applied to thesubstrate.

SUMMARY OF THE INVENTION

[0004] What is yet needed is a method for coating microelectromechanical devices that provides a relatively corrosion-resistantand electrically insulating coating on at least one surface of thedevice. Furthermore, it is highly desirable to coat the device at arelatively low temperature that will likely increase the fabricationprocess because substantially all of the device components and featurescan be assembled prior to coating the device. For example, in a typicaldevice fabrication process, a corrosion-resistant coating is applied toindividual components along the fabrication process but prior tocomplete assembly of the device. Because typical coating methods utilizerelatively high temperatures, coating a completely assembled device isgenerally not possible because the relatively high coating temperaturestend to be detrimental to electrical components that, in turn, mayultimately adversely affect the functioning of the device.

[0005] As used herein, “corrosion” refers to a complex electrochemicaldegradation of a conductive material (such as a metal or a metal alloy)or a semiconductive material (such as silicon or carbon) due to areaction between such materials and the environment, usually an aqueouselectrolyte-containing environment that can be an acidic or basic(alkaline) environment. In general, a corrosion product of such amaterial is in the form of an oxide of the material, such as a metaloxide, silicon dioxide, and the like. While not wishing to be bound byany particular theory, it is believed that corrosion occurs when thematerial (such as copper or silicon) contacts an electolytic solutionand a mini-electrochemical circuit is formed when a small amount of thematerial dissolves in the water and combines with oxygen or otherdissolved species. In forming the mini-electrochemical circuit, animbalance of electrons between the solution and the surrounding materialcreates a minute flow of electrons, or current. So long as a current isallowed to flow, the material will continue to deteriorate, resulting indegradation and even pitting of the material. An electrically insulatingcoating is one that prevents completion of the current in the“minielectrochemical curcuit.”

[0006] Accordingly, one aspect of the present invention provides amethod for coating an implantable device. Preferably, coating theimplantable device is accomplished at a low temperature. “Lowtemperature,” as used herein, means that an input of energy to increasethe temperature during plasma deposition is not required. In accordancewith the present invention, plasma deposition preferably occurs at aboutambient temperature, typically from about 20EC to about 30EC.

[0007] A method for coating a surface of an implantable devicepreferably includes plasma pretreating at least one surface of theimplantable device with an inert gas; providing the implantable deviceto a plasma reaction chamber; and plasma treating the at least onesurface of the implantable device with a reactant monomer to form acoating thereon. “Inert” refers to relative chemical inactivity of acompound under ambient conditions however, under some plasma depositionconditions the “inert” compound may become reactive when a glowdischarge of the compound is created.

[0008] Preferably, the reactant monomer is selected from the groupconsisting of a substituted or unsubstituted alkene, arene, silane,siloxane, and a combination thereof. More preferably, the reactantmonomer is selected from the group consisting of ethylene,2-methyl-1-pentene, xylene, divinylmethylsilane, hexamethyldisilane,tetramethylsiloxane, and a combination thereof.

[0009] A method in accordance with the present invention preferablyincludes plasma treating the at least one surface by creating a glowdischarge of the reactant monomer in the presence of an inert gas. Theinert gas is preferably selected from the group of argon, helium,nitrogen, neon, and a combination thereof. The reactant monomer ispreferably in a ratio with the inert gas of about 3 parts to about 6parts reactant monomer to about 1 part inert gas.

[0010] A method in accordance with the present invention preferablyincludes plasma treating the at least one surface by creating a glowdischarge of the reactant monomer using a power of about 30 Watts toabout 100 Watts for a time period from about 10 minutes or less.Preferably, the method includes a pressure within the reaction chamberof about 0.025 Torr to about 0.1 Torr.

[0011] In accordance with the present invention, plasma pretreating theat least one surface includes supplying the inert gas to the reactionchamber at a flow rate of about 2 sccm. Preferably, plasma pretreatingthe at least one surface includes a pressure in the reaction chamber ofabout 5 mTorr to about 15 mTorr. Plasma pretreating the at least onesurface preferably includes generating a glow discharge of the inert gasusing radio frequency (abbreviated herein “R.F.”) power of about 100Watts for a time of about 2 minutes or less.

[0012] Additionally, a method in accordance with the present inventionmay further include cleaning the at least one surface prior to plasmatreating the at least one surface with a reactant monomer. Preferably,cleaning the at least one surface is accomplished prior to plasmapretreating the at least one surface.

[0013] Also in accordance with the present invention, the method mayfurther include adding a polymer to the at least one surface having acoating thereon, wherein the polymer is selected from the groupconsisting of a natural hydrogel, a synthetic hydrogel, silicone,polyurethane, polysulfone, cellulose, polyethylene, polypropylene,polyamide, polyimide, polyester, polytetrafluoroethylene, polyvinylchloride, epoxy, phenolic, neoprene, polyisoprene, and a combinationthereof. The method may also include adding a bio-active compound to theat least one surface having a coating thereon. Preferably, thebio-active compound is selected from the group consisting of anantithrombotic agent, an antiplatelet agent, an antimitotic agent, anantioxidant, an antimetabolite agent, an anti-inflammatory agent, and acombination thereof.

[0014] An implantable device coated in accordance with the presentinvention can be selected from the group consisting of a pacemaker, apacemaker-cardioverter-defibrillator, an implantable neurostimulator, amuscle stimulator, an implantable monitoring device, an implantablefluid handling device, a defibrillator, a cardioverter/defibrillator, agastric stimulator, a drug pump, and a hemodynamic monitoring device.

[0015] Another aspect of the present invention provides an implantabledevice including at least one surface coating formed by the methoddescribed above. Preferably, the coating has a thickness of about 200 Δto about 2000 Δ. In accordance with the present invention, the at leastone surface can include a metal, a nonmetal, and a combination thereof.

[0016] Yet another aspect of the present invention provides animplantable device including at least one surface having a coatingformed thereon from a compound selected from the group consisting ofethylene, 2-methyl-1-pentene, xylene, divinylemthylsilane,hexamethyldisilane, and tetramethylsiloxane.

[0017] As used herein, “reactant” monomer refers to a branched orunbranched hydrocarbon that can be plasma deposited on a substrate,preferably at a relatively low temperature. The hydrocarbon can beclassified as an aliphatic monomer, a cyclic monomer, or it can includea combination of aliphatic and cyclic groups (e.g., alkaryl and aralkylgroups), wherein the hydrocarbon may include one or more heteroatoms,such as nitrogen, oxygen, sulfur, silicon, etc. In the context of thepresent invention, the term “aliphatic” means a saturated or unsaturatedlinear or branched hydrocarbon. This term is used to encompass alkyl,alkenyl, and alkynyl compounds, for example. The term “alkyl” means asaturated linear or branched hydrocarbon; including, for example,methane, ethane, isopropane, t-butane, heptane, dodecane, and the like.The term “alkenyl” means an unsaturated linear or branched hydrocarbonwith one or more carbon-carbon double bonds, such as a vinyl-containingcompound. The term “alkynyl” means an unsaturated linear or branchedhydrocarbon with one or more triple bonds. The term “cyclic” means aclosed ring hydrocarbon that is classified as an alicyclic, aromatic, orheterocyclic compound. The term “alicyclic” means a cyclic hydrocarbonhaving properties resembling those of aliphatic hydrocarbons. The term“aromatic” or “arene” compound means a mono- or polynuclear aromatichydrocarbon.

[0018] A method in accordance with the present invention is suitable forany implantable device but is particularly well suited for microeletromechanical devices, such as implantable pumps, filters, valves,cardiac pacesetters, and the like.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019]FIG. 1 is a schematic of an apparatus for use in a coating methodin accordance with the present invention.

DETAILED DESCRIPTION

[0020] Coating at least one surface of an implantable device thatprovides a relatively corrosion-resistant coating on at least onesurface of the device preferably includes plasma deposition of areactant monomer, preferably a reactant monomer selected from the groupconsisting a substituted or unsubstituted alkene, arene, silane,siloxane, and a combination thereof. More preferably, the reactantmonomer is selected from the group consisting of ethylene, xylene,2-methyl 1-pentene, divinylmethylsilane, hexamethyldisilane,tetramethyldisiloxane, and a combination thereof.

[0021] Suitable plasma reactors are known in the art, examples of whichare described by Yasuda, H., Plasma Polymerization, Academic Press(Orlando, Fla., 1985); and d'Agostino, R., Plasma Deposition, Treatment,and Etching of Polymers, Academic Press (San Diego, Calif., 1990).Typically, such plasma reactors use short wave energy (RF or microwave)to excite plasma.

[0022] In general, a plasma reactor for use in the present invention-caninclude a glass reaction chamber that is fitted with a vacuum exhaust,gas inlets and at least one capacitively coupled electrode. In addition,the reactor is fitted with a pressure transducer and a mass flowcontroller for controlling and measuring the amount of gas beingintroduced into the reactor. The theory and practice of radio frequency(RF) gas discharge is explained in detail in 1) “Gas-DischargeTechniques For Biomaterial Modifications” by Gombatz and Hoffman, CRCCritical Reviews in Biocompatibility. Vol. 4, Issue 1 (1987) pp 1-42; 2)“Surface Modification and Evaluation of Some Commonly Used CatheterMaterials, I. Surface Properties” by Triolo and Andrade, Journal ofBiomedical Materials Research, Vol. 17, 129-147 (1983), and 3) “SurfaceModification and Evaluation of Some Commonly Used Catheter Materials,II. Friction Characterized” also by Triolo and Andrade, Journal ofBiomedical Materials Research, Vol. 17, 149-165 (1983).

[0023]FIG. 1 illustrates in schematic form a plasma reactor 10 that canbe employed in a method in accordance with the present invention. Theplasma reactor 10 includes, in general, a vertical reaction chamber 12,R.F. power source 14 coupled across upper and lower electrodes 16 and18, vacuum pump 20 and a reactant monomer source 22 in fluidcommunication with the reaction chamber 12. Preferably, the reactantmonomer source 22 also includes a means for controlling the flow rate ofthe reactant monomer (not shown).

[0024] A substrate having at least one surface 24 to be coated isdisposed on one electrode, for example, the lower electrode 18.Optionally, the electrode 18 can be brought to a suitable temperature bya heating/cooling unit (not shown) that may be located in closeproximity to electrode 18 and electrically controlled by a temperaturecontrol unit (not shown). Preferably, a plasma deposition method inaccordance with the present invention does not require the input ofenergy for heating or cooling, so that the deposition takes place at arelatively low temperature, more preferably ambient temperature(typically about 20EC to about 30EC). However, it will be recognized bythose with ordinary skill in the art that although plasma depositiontakes place at a relatively low temperature, the temperature of thesurface so coated may increase slightly, typically to a temperature justslightly warmer than ambient temperature to the touch.

[0025] Optionally, a bellows (not shown) may be provided to adjust thespacing between the electrodes and, hence, controlling the confinementof the plasma 40. Preferably, a throttle valve 34 may be provided tocontrol the pressure in the reaction chamber 12. The parameters thattypically control the film characteristics formed from the reactantmonomer include gas composition, gas flow rate, R.F. power, pressure,and temperature. Typically, the R.F. power can range from about 30 Wattsto about 100 Watts, but is preferably at about 40 Watts for reactantmonomer deposition. The pressure is typically about 0.025 Torr to about1.0 Torr. Preferably, a glow discharge of the reactant monomer iscreated by using the R.F. power above for a period of time of about 10minutes or less, more preferably, from about 15 seconds to about 5minutes, and even more preferably from about 1 minute to about 4minutes.

[0026] Preferably, the reactant monomer is introduced into the reactionchamber with an inert gas from source 38 that may be in fluidcommunication with the reaction chamber 12. An inert gas can be selectedfrom the group of argon, helium, nitrogen, neon, and the like.Preferably, the inert gas is argon. Combinations of the inert gases canalso be beneficial to make the initiation of discharge (i.e., generationof the plasma) easier. For example, argon can be added to neon in aminor amount that may improve plasma initiation.

[0027] The reactant monomer is preferably provided to the reactionchamber in a ratio with the inert gas of about 3 parts to about 6 parts,preferably about 3 parts to about 5 parts, reactant monomer to about 1part inert gas. For example, the reactant monomer gas flow rate ispreferably about 8 sccm to about 12 sccm, more preferably about 9 sccmto about 10 sccm, and the inert gas flow rate is preferably about 2sccm. Of course, one skilled in the art will readily appreciate that thedeposition rate of the reactant monomer depends on the gas compositionand is directly proportional to the gas flow rate, power, pressure, andis inversely proportional to temperature so that one could empiricallydetermine the optimum parameters, such as those indicated above, fordesired film characteristics.

[0028] For example, in one embodiment, the operating pressure can beabout 0.1 Torr. The reactant monomer can be supplied at a rate of about10 sccm and an inert gas can be supplied at a rate of about 2 sccm. Aglow discharge can be created by supplying R.F. power of about 40 Wattsfor a period of time of about 2 minutes. Preferably, the reactantmonomer is selected from the group consisting of ethylene,2-methyl-1-pentene, xylene, divinylmethylsilane, hexamethyldisilane,tetramethyldisiloxane, and a combination thereof. Preferably, the inertgas is argon.

[0029] A surface to be coated in accordance with the present inventionis plasma pretreated to further prepare the surface prior to coating.For example, the surface can be pretreated in a plasma reactor, such asdescribed above. An inert gas, such argon, can be supplied to thereaction chamber at a flow rate of about 2 sccm. The operating pressurecan be about 5 mTorr to about 15 mTorr. A glow discharge can be createdusing an R.F. power of about 100 Watts for a time of about 2 minutes orless.

[0030] Preferably, prior to plasma depositing a reactant monomer on adevice surface, the surface to be coated is thoroughly cleaned to removeany contaminating debris and the like. More preferably, the surface tobe coated in accordance with the present invention is first cleaned andplasma pretreated prior to plasma depositing the reactant monomer.Conventional techniques can be used to adequately clean the surface,such as applying typical cleaning solvents (e.g., isopropyl alcohol,acetone, and the like) and/or ultrasonic cleaning in an aqueoussolution, solvent cleaning, and the like. For example, the device to becoated can be placed in a conventional ultrasonic bath containing anaqueous detergent solution for cleaning and then subsequently rinsed toremove detergent prior to coating.

[0031] Although the foregoing was described with particular attention tothe corrosion-resistance of a coating formed in accordance with thepresent invention, it is to be understood by those skilled in the artthat such a coating can also be utilized in other applications. Forexample, a coating formed in accordance with the present invention canbe used as an adhesion promoting primer to enhance adhesion of a secondcoating to the device, as a barrier layer for electronic contacts anddevices, and a passivating layer.

[0032] For example, once a surface of a device has been coated asdescribed above, a polymer can now be applied to the coated surface byconventional methods by dipping, spraying, or other applicationtechniques. Polymers particularly suitable include a natural hydrogel, asynthetic hydrogel, silicone, polyurethane, polysulfone, cellulose,polyethylene, polypropylene, polyamide, polyimide, polyester,polytetrafluoroethylene (TEFLON), polyvinyl chloride, epoxy, phenolic,neoprene, polyisoprene, and a combination thereof. Additionally, abio-active compound can be adhered to a surface coated in accordancewith the present invention. The bio-active compound can be applieddirectly to the surface that has been plasma treated, as describedabove, or the surface that has been plasma treated and includes thepolymer adhered thereto. A suitable bio-active compound can be selectedfrom the group consisting of an antithrombotic agent, an antiplateletagent, an antimitotic agent, an antioxidant, an antimetabolite agent, ananti-inflammatory agent, and a combination thereof. For example, onepreferred bio-active compound is heparin. The subsequent addition of apolymer and/or a bio-active compound can be accomplished utilizingconventional techniques known in the art, such as described by Y. Ikada,“Surface Modification of Polymers for Medial Applications,”Biomaterials, Vol. 15:725-736 (1994); E. A. Kulik, et al., “PeroxideGeneration and Decomposition on Polymer Surface,” J. of Polymer Science:Part A: Polymer Chemistry, Vol. 33:323-330 (1995); and K. Allm

r et al., J. of Polymer Science, Vol. 28:173-183 (1990), for example.

[0033] An implantable device may be any implantable device. For example,in the case where the implantable device is a pacemaker, the implantabledevice may be a pacemaker such as that described in U.S. Pat. No.5,158,078 to Bennett, et al.; U.S. Pat. No. 5,312,453 to Shelton et al.;or U.S. Pat. No. 5,144,949 to Olson et al.

[0034] Implantable device may also be apacemaker-cardioverter-defibrillator (PCD) corresponding to any of thevarious commercially-available implantable PCDs. For example, thepresent invention may be practiced in conjunction with PCDs such asthose described in U.S. Pat. No. 5,545,186 to Olson, et al.; U.S. Pat.No. 5,354,316 to Keimel; U.S. Pat. No. 5,314,430 to Bardy; U.S. Pat. No.5,131,388 to Pless; or U.S. Pat. No. 4,821,723 to Baker, et al.

[0035] Alternatively, an implantable device may be an implantableneurostimulator or muscle stimulator such as that disclosed in U.S. Pat.No. 5,199,428 to Obel, et al.; U.S. Pat. No. 5,207,218 to Carpentier, etal.; or U.S. Pat. No. 5,330,507 to Schwartz, or an implantablemonitoring device such as that disclosed in U.S. Pat. No. 5,331,966 toBennett, et al.

[0036] Additionally, the implantable device may be micromachined devicessuch as implantable fluid handling devices for continuous administrationof therapeutic agents including those for pain management, cancerchemotherapy, treatment of intractable spasticity, to name a few. Suchdevices are described in, for example, U.S. Pat. Nos. 5,705,070;5,702,618; and 5,660,728 all to Saaski et al.

[0037] Further, for example, an implanted device may be a defibrillator,a cardioverter/defibrillator, a brain stimulator, a gastric stimulator,a drug pump, a hemodynamic monitoring device, or any other implantabledevice that would benefit from a coating for protection againstcorrosion. Therefore, the present invention is believed to find wideapplication in any form of implantable device. As such, the descriptionherein making reference to any particular medical device is not to betaken as a limitation of the type of medical device that can beprotected from corrosion as described herein.

[0038] In accordance with the present invention, at least one surface ofan implantable device can be coated as described above. The at least onesurface can be formed from a material selected from the group consistingof a metal (including alloys), a nonmetal, and a combination thereof.“Metal” refers to a group of compounds that tend to form positive ionswhen the compounds are in solution and include alkali metals, alkalineearth metals, transition metals, noble metals, rare metals, rare earthmetals, to name a few. “Nonmetal” refers to a group of compounds that,in general, have very low to moderate conductivity and relatively highelectronegativity and include germanium-, selenium-, andsilicon-containing compounds, to name a few. Metals and nonmetals areboth intended to include oxides and nitrides, and combinations thereof.For example, suitable materials that can be plasma treated in accordancewith the present invention include gold, stainless steel, silicon, toname a few. The at least one surface may be located on the exteriorsurface, interior surface, or both, of an implantable device.

EXAMPLES

[0039] While surface modification methods and apparatuses in accordancewith the invention have been described herein, the followingnon-limiting examples will further illustrate the invention.

[0040] In each of the following examples, silicon wafers having a sizeof about 1 cm² were coated as described below. Prior to plasma coating areactant monomer on the surface of the wafer, each wafer was thoroughlycleaned. First, the wafers were cleaned by placing the wafers into abeaker containing acetone and soaked for 10 minutes at room temperature.The wafers were then removed from the acetone and placed in isopropylalcohol and soaked for 10 minutes at room temperature. A beaker wasfilled with a cleaning solution of 30 parts DI water to 1 part cleaningsolution commercially available under the trade designation of ULTRAMET,from Buehler, Lake Bluff, Ill. Water was then placed in a conventionalultrasonic cleaner commercially available under the trade designation ofULTRASONIC CLEANER, from Branson Cleaning Equipment Co., Shelton, Conn.,to a depth of at least ¼ the height of the beaker. The wafers wereplaced in the cleaning solution in the beaker. The beaker containing thewafers in the cleaning solution were placed into the ultrasonic cleaner.The ultrasonic cleaner was set for a cleaning time of 3 minutes.

[0041] The wafers were then removed from the cleaning solution andplaced on a drying rack. The wafers were rinsed thoroughly with DI waterby rinsing 5 times with 2 quarts of DI water at ambient conditions. Thewafers were then removed and placed on rice paper to dry for at leastone half hour at ambient conditions.

[0042] Plasma pretreatment was applied directly to a cleaned siliconwafer surface. The wafer was placed in a plasma reaction chamber asdescribed above and shown in FIG. 1. The wafers were placed on the lowerelectrode. The reaction chamber was evacuated to an initial pressure ofless than about 5 mTorr. The operating pressure for plasma pretreatmentwas set at 11 mTorr and the reaction chamber was allowed to equilibratefor 15 minutes. Mass flow controllers were used to meter the argon gasinto the reaction chamber at the rate of 2 sccm. A glow discharge wascreated by putting a 100 Watt RF power load on the electrodes for 1minute exposure time.

[0043] All wafers, whether pretreated or not, were coated using a plasmareactor as described above and the parameters for reactant monomerdeposition are recited for each example below.

Example 1

[0044] A silicon wafer that was not cleaned and pretreated as describedabove was placed in the plasma reaction chamber. The wafer was placed onthe lower electrode. The reaction chamber was evacuated to a basepressure of 5 mTorr. The operating pressure was set 0.1 Torr and thereaction chamber was allowed to equilibrate for 15 minutes. Mass flowcontrollers were used to meter the ethylene flow at a rate of 15 sccmand the argon gas into the reaction chamber at the rate of 2 sccm. Aglow discharge was created by putting a 100 Watt RF power load on theelectrodes for 1 minute exposure time.

[0045] Under these conditions, a blue coating was visually observed onthe wafer. The durability of the coated was evaluated by wiping thecoated wafer surface with a laboratory tissue commercially availableunder the trade designation KIMWIPE (Kimberly Clark Corporation,Roswell, Ga.) with isopropyl alcohol. The coated surface scratchedeasily under these conditions.

Example 2

[0046] A cleaned and plasma pretreated silicon wafer, as describedabove, was placed in the plasma reaction chamber and plasma coated usingthe same conditions as described in Example 1.

[0047] Under these conditions, a blue coating was visually observed onthe wafer. The durability of the coated was evaluated by wiping thecoated wafer surface with a laboratory tissue commercially availableunder the trade designation KIMWIPE with isopropyl alcohol. The coatedsurface did not scratch under these conditions. To further evaluatedurability, the coated wafer was cut in half, where a first half wasplaced in a 1N aqueous solution of sodium hydroxide and the second halfwas placed in a 1N aqueous solution of hydrochloric acid. Each half wassoaked in the respective solution for 40 hours at room temperature. Thecoating on the first half of the wafer was observed with the naked eyeas having many “pore-like” openings. The coating on the second half ofthe wafer lifted off the wafer surface after soaking in the hydrochloricacid solution.

Example 3

[0048] A cleaned and plasma pretreated silicon wafer was plasma coatedwith 2-methyl-1-pentene. After plasma pretreating the wafer for 1minute, the RF power remained at 100 Watts and the operating pressurewas increased to 0.1 Torr and the reaction chamber was allowed toequilibrate for 15 minutes. Thereafter, the RF power was decreased to 40Watts. Mass flow controllers were used to meter the 2-methyl-1-penteneflow at a rate of 10 sccm and the argon gas into the reaction chamber atthe rate of 2 sccm. A glow discharge was created by putting the 40 WattRF power load on the electrodes for 2 minutes exposure time. A coatingwas produced on the wafer surface that had a thickness of 750Δ.

[0049] Under these conditions, a smooth blue coating was visuallyobserved on the wafer. Using a conventional dissecting microscope at amagnification of 10×, holes in the coating could not be detected. Thedurability of the coated was evaluated by wiping the coated wafersurface with a laboratory tissue commercially available under the tradedesignation KIMWIPE with isopropyl alcohol. The coated surface did notscratch under these conditions. To further evaluate durability, thecoated wafer was placed in a 1N aqueous solution of sodium hydroxide for16 hours at room temperature. The coating on the wafer was observedunder 10× magnification as having many “pore-like” openings.

Example 4

[0050] A cleaned and pretreated silicon wafer was coated with2-methyl-1-pentene as described in Example 3 with the only exceptionbeing that the glow discharge was created by putting the 40 Watt RFpower load on the electrodes for 4 minutes exposure time. A coating wasproduced on the wafer surface that had a thickness of 575Δ.

Example 5

[0051] A gold wafer was coated with 2-methyl-1-pentene as described inExample 3, except as follows. The gold wafer was placed in a plasmareaction chamber as described above and shown in FIG. 1. The wafers wereplaced on the lower electrode. The reaction chamber was evacuated to abase pressure of 5 mTorr. The operating pressure was set 0.03 Torr andthe reaction chamber was allowed to equilibrate for 15 minutes. Massflow controllers were used to meter the argon gas into the reactionchamber at the rate of 2 sccm. A glow discharge was created by putting a100 Watt RF power load on the electrodes for 30 seconds exposure time.

[0052] After plasma pretreating the wafer for 30 seconds, the RF powerremained at 100 Watts and the 2-methyl-1-pentent was added to thereaction chamber that was allowed to equilibrate for 5 minutes.Thereafter, the RF power was decreased to 40 Watts. Mass flowcontrollers were used to meter the 2-methyl-1-pentene flow at a rate of9.6 sccm and the argon gas into the reaction chamber at the rate of 2sccm. A glow discharge was created by putting the 40 Watt RF power loadon the electrodes for 10 minutes exposure time. A coating was producedon the wafer surface that had a thickness of 1640Δ.

Example 6

[0053] A cleaned and plasma pretreated silicon wafer was plasma coatedwith 2-methyl-1-pentene. After plasma pretreating the wafer for 1minute, the RF power remained at 100 Watts and the operating pressurewas increased to 0.1 Torr and the reaction chamber was allowed toequilibrate for 15 minutes. Thereafter, the RF power was decreased to 40Watts. Mass flow controllers were used to meter the 2-methyl-1-penteneflow at a rate of 10 sccm and the argon gas into the reaction chamber atthe rate of 2 sccm. A glow discharge was created by putting the 40 WattRF power load on the electrodes for 2 minutes exposure time. A coatingwas produced on the wafer surface that had a thickness of 750Δ.

[0054] Under these conditions, a smooth blue coating was visuallyobserved on the wafer. Using a conventional dissecting microscope at amagnification of 10×, holes in the coating could not be detected. Thedurability of the coated was evaluated by wiping the coated wafersurface with a laboratory tissue commercially available under the tradedesignation KIMWIPE with isopropyl alcohol. The coated surface did notscratch under these conditions. To further evaluate durability, thecoated wafer was placed in a 1N aqueous solution of sodium hydroxide for16 hours at room temperature. The coating on the wafer was observedunder 10× magnification as having many “pore-like” openings.

Example 7

[0055] A cleaned and plasma pretreated silicon wafer was plasma coatedwith tetramethyldisiloxane (TMDSO) under the same conditions asdescribed in Example 6. A coating was produced on the wafer surface thathad a thickness of 750Δ.

[0056] Under these conditions, a smooth blue coating was visuallyobserved on the wafer. Using a conventional dissecting microscope at amagnification of 10×, holes in the coating could not be detected. Thedurability of the coated was evaluated by wiping the coated wafersurface with a laboratory tissue commercially available under the tradedesignation KIM WIPE with isopropyl alcohol. The coated surface did notscratch under these conditions. To further evaluate durability, thecoated wafer was placed in a 1N aqueous solution of sodium hydroxide for16 hours at room temperature. The coating on the wafer was observedunder 10× magnification as having many “pore-like” openings.

Example 8

[0057] A cleaned and plasma pretreated silicon wafer was plasma coatedwith divinylmethylsilane under the conditions described in Example 6. Acoating was produced on the wafer surface that had a thickness of 750Δ.

[0058] Under these conditions, a smooth blue coating was visuallyobserved on the wafer. Using a conventional dissecting microscope at amagnification of 10×, holes in the coating could not be detected. Thedurability of the coating was evaluated by wiping the coated wafersurface with a laboratory tissue commercially available under the tradedesignation KIMWIPE with isopropyl alcohol. The coated surface did notscratch under these conditions. To further evaluate durability, thecoated wafer was placed in a 1N aqueous solution of sodium hydroxide for16 hours at room temperature. The coating on the wafer was observedunder 10× magnification as having many “pore-like” openings.

[0059] The complete disclosures of all patents, patent applications, andpublications are incorporated herein by reference as if individuallyincorporated. The above disclosure is intended to be illustrative andnot exhaustive. The description will suggest many variations andalternatives to one of ordinary skill in this art. All thesealternatives and variations are intended to be included within the scopeof the attached claims. Those familiar with the art may recognize otherequivalents to the specific embodiments described herein whichequivalents are also intended to be encompassed by the claims attachedthereto.

What is claimed is:
 1. A method for coating a surface of an implantabledevice comprising: plasma pretreating at least one surface of theimplantable device with an inert gas; providing the implantable deviceto a plasma reaction chamber; and plasma treating the at least onesurface of the implantable device with a reactant monomer to form acoating thereon.
 2. The method of claim 1, wherein plasma treating theat least one surface comprises a low temperature within the reactionchamber.
 3. The method of claim 1, wherein the reactant monomer isselected from the group consisting of a substituted or unsubstitutedalkene, arene, silane, siloxane, and a combination thereof.
 4. Themethod of claim 3, wherein the reactant monomer is selected from thegroup consisting of ethylene, 2-methyl-1-pentene, xylene,divinylmethylsilane, hexamethyldisilane, tetramethylsiloxane, and acombination thereof.
 5. The method of claim 1, wherein plasma treatingthe at least one surface comprises creating a glow discharge of thereactant monomer in the presence of an inert gas.
 6. The method of claim5, wherein the inert gas is selected from the group of argon, helium,nitrogen, neon, and a combination thereof.
 7. The method of claim 5,wherein the reactant monomer is in a ratio with the inert gas of about 3parts to about 6 parts reactant monomer to about 1 part inert gas. 8.The method of claim 1, wherein plasma treating the at least one surfacecomprises creating a glow discharge of the reactant monomer using apower of about 30 Watts to about 100 Watts for a time period from about10 minutes or less.
 9. The method of claim 1, wherein plasma pretreatingthe at least one surface comprises supplying the inert gas to thereaction chamber at a flow rate of about 2 sccm.
 10. The method of claim1, wherein plasma pretreating the at least one surface comprises apressure within the reaction chamber of about 5 mTorr to about 15 mTorr.11. The method of claim 1, wherein plasma pretreating the at least onesurface comprises generating a glow discharge of the inert gas using anR.F. power of about 100 Watts for a time of about 2 minutes or less. 12.The method of claim 1 further comprising cleaning the at least onesurface prior to plasma treating the at least one surface with areactant monomer.
 13. The method of claim 1, wherein plasma treating theat least one surface with the reactant monomer comprises a pressurewithin the reaction chamber of about 0.025 Torr to about 0.1 Torr. 14.The method of claim 1 further comprising adding a polymer to the atleast one surface having the coating thereon, wherein the polymer isselected from the group consisting of a natural hydrogel, a synthetichydrogel, silicone, polyurethane, polysulfone, cellulose, polyethylene,polypropylene, polyamide, polyimide, polyester, polytetrafluoroethylene,polyvinyl chloride, epoxy, phenolic, neoprene, polyisoprene, and acombination thereof.
 15. The method of claim 1 further comprising addinga bio-active compound to the at least one surface having the coatingthereon.
 16. The method of claim 15, wherein the bio-active compound isselected from the group consisting of an antithrombotic agent, anantiplatelet agent, an antimitotic agent, an antioxidant, anantimetabolite agent, an anti-inflammatory agent, and a combinationthereof.
 17. The method of claim 1, wherein the implantable device isselected from the group consisting of a pacemaker, apacemaker-cardioverter-defibrillator, an implantable neurostimulator, amuscle stimulator, an implantable monitoring device, an implantablefluid handling device, a defibrillator, a cardioverter/defibrillator, agastric stimulator, a drug pump, and a hemodynamic monitoring device.18. An implantable device comprising at least one surface coated by themethod according to claim
 1. 19. The implantable device of claim 1,wherein the coating has a thickness of about 200 Δ to about 2000 Δ. 20.The implantable device of claim 1, wherein the at least one surfacecomprises a metal, a nonmetal, and a combination thereof.
 21. Animplantable device comprising at least one surface having a coatingformed thereon from a compound selected from the group consisting ofethylene, 2-methyl-1-pentene, xylene, divinylmethylsilane,hexamethyldisilane, and tetramethylsiloxane.